diff options
Diffstat (limited to 'src/backend/commands/sequence.c')
| -rw-r--r-- | src/backend/commands/sequence.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c index be04177a2ee..de6e2a3e33f 100644 --- a/src/backend/commands/sequence.c +++ b/src/backend/commands/sequence.c @@ -427,8 +427,8 @@ AlterSequence(AlterSeqStmt *stmt) FormData_pg_sequence new; List *owned_by; - /* open and AccessShareLock sequence */ - relid = RangeVarGetRelid(stmt->sequence, false); + /* Open and lock sequence. */ + relid = RangeVarGetRelid(stmt->sequence, AccessShareLock, false, false); init_sequence(relid, &elm, &seqrel); /* allow ALTER to sequence owner only */ @@ -507,7 +507,16 @@ nextval(PG_FUNCTION_ARGS) Oid relid; sequence = makeRangeVarFromNameList(textToQualifiedNameList(seqin)); - relid = RangeVarGetRelid(sequence, false); + + /* + * XXX: This is not safe in the presence of concurrent DDL, but + * acquiring a lock here is more expensive than letting nextval_internal + * do it, since the latter maintains a cache that keeps us from hitting + * the lock manager more than once per transaction. It's not clear + * whether the performance penalty is material in practice, but for now, + * we do it this way. + */ + relid = RangeVarGetRelid(sequence, NoLock, false, false); PG_RETURN_INT64(nextval_internal(relid)); } |